1. Field of the Invention
The present invention pertains, in general, to a red, green, and blue light emitting diode (RGB LED) package and, more particularly, to an RGB light emitting diode package, which employs a photomixing material to assure excellent color mixing properties in a relatively small area, thereby making slimness thereof possible.
2. Description of the Prior Art
A light emitting diode densely emits rays having transparent colors in a high degree of efficiency. Additionally, the light emitting diode does not burn easily due to heat, and is a semiconductor element, and thus, it has excellent primary operational characteristics, high resistance to vibration, and durability with regard to repeated on/off operations. Hence, the light emitting diode is applied to various indicators and light sources.
Recently, applications of the light emitting diode are expanding, for example, it is used as an illuminator. The light emitting diode is produced by using gallium arsenide (GaAs), gallium phosphide (GaP), gallium nitride (GaN), and silicon carbide (SiC) depending on the desired light color, intensity of illumination and the like, and its PN junction part can emit visible rays at a relatively low voltage when it is biased in an avalanche breakdown region. In the case of the indicator, power is applied through a multiplexing network in order to reduce a power consumption, and the light emitting diode serves to change a structure of the indicator to emit rays with different wavelengths. The light emitting diode may be individually used or may be used in a form of matrix structure.
Recently, a RGB (red, green, and blue) light emitting diode with ultra-high luminousness and high efficiency has been developed, and an LED display with a large-sized screen has appeared, which employs such a light emitting diode. The LED display is advantageous in that it has excellent characteristics, for example it is operated with low power, lightweight, and has a long life, and thus, it is believed that the LED display will be applied to various fields.
Many efforts have been made to develop a white light source using a light emitting diode. Since the light emitting diode has an emission spectrum useful for generating monochromatic light, it is necessary to arrange three luminous components of R, G, and B in such a manner that they are in close proximity to each other to diffuse and mix different rays, emitted from the components, with each other so as to generate a light source for white light. When white light is generated by the arrangement, white light with a desired tone may be not obtained because of changes in a tone of color, brightness, and other factors of the luminous components.
Furthermore, if the luminous components are made from different materials, the power required to generate light is different among the different luminous components, and thus, it is necessary to apply different voltages to the different luminous components, resulting in inconvenience in the production of a complicated circuit. Moreover, since the luminous components consist of luminous semiconductor components, the tone may be changed or nonuniform color may be obtained due to temperature characteristics, chronological variations, and differences between operation devices, making a uniform mixing of rays, emitted from the luminous components, impossible.
Generation of white light using an RGB light emitting diode in a conventional manner is shown in FIG. 1. As shown in FIG. 1, red, green, and blue light emitting diode (LED) chips 2 operable to emit light rays 1 are provided on a reflector 3. A filler resin 4 encapsulates LED chips 2 and reflector 3. Since colors (rays 1) are mixed depending on a directive angle of a chip, a predetermined distance must be assured to make the uniform mixing of colors possible. Alternatively, there is a method of mounting individual chips in a form of lens, but in this method, there is a limit to uniformly mix colors and it is cumbersome to design a complicated lens.
Accordingly, even though the light emitting diode is an effective light emitting device for generating separate colors, it cannot be yet used as a desired light source for emitting white light employing the luminous components.
Meanwhile, recently, an RGB light emitting diode package, which has a very thin structure and employs LED chips having high brightness, has been preferred. However, the RGB light emitting diode package is problematic in that there is a limit to uniformly mix colors in the package because of a restriction in an area.